Adjustable ohaie



(No Model.) 4 SheetsSheet 1. W. E. BURK.

ADJUSTABLE CHAIR.

No. 320,844. Patented June 23, 1885.

' INVENTOR WZZlZa/nE'. Bur

By his .dttorneyg n. PETERS. Phdlo-Lhhagnphlr. Wuhlngfcn. no.

4 K R U B E ADJUSTABLE CHAIR.

Patented June 23, 1885.

INVENTOR WE'ZZz'am 1 73a r71 By his .dlforne s u. PETERS. FhutoLithngr-apber. Washington, 0.1:.

(No Model.) 4 Sheets-Sheet 3. W. E. BURK.

ADJUSTABLE CHAIR.

No. 320,844. PatentedJune' Z3,

William E'.Burk

N. PETER Phnla-[Mogaphfm Wishinliun. DJ:-

(No Model.)

4 Sheets-Sheet 4. W. E. BURK.

ADJUSTABLE CHAIR.

Patented Ju qne 2 3, 1885.

WITNESSES INVENTOR mZZz'c/zmEBurk UNITED STATES PATENT OFFICE.

\VILLIAM BURK, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THE S. S. \VHITE DENTAL MANUFACTURING COMPANY, OF SAME PLACE.

ADJUSTABLE CHAIR.

SPECIFICATION forming part of Letters PatentNo. 320,844, dated June 23, 1885,

Application filed November 8, 1883.

T0 at whom it may concern:

Be it known that 1, WILLIAM E. BURK, of the city and county of Philadelphia, in the State of Pennsylvania, have invented certain new and useful Improvements in Adjustable Chairs, of which the following is a specification.

My invention relates more especially to adjustable chairs for the use of dentists; and its objects are to provide a chair the parts of which are readily adjustable so as to secure the ease and comfort of the patient, as well as the placing of the patient in the best positions for the operation to be performed.

My object, more especially is to provide a chair having all the necessary adjustments, which presents a nice appearance, and can be comparatively cheaply manufactured.

The subject-matter claimed herein as my invention is first particularly described in detail as organized in the best way now known to me, and is then particularly pointed out in the claims at the close of the specification.

Some of my improvements may be used without the others.

In the accompanying drawings, which show the best way now known to me of embodying my improvements, Figure l is a view in elevation of my improved chair. Fig. 2 is a ver tical central section through the frame-work and seat portion thereof on the line 2 2 of Fig. 4. Fig. 3 is a horizontal section on the line 3 3 of Fig. 1. Fig. 4 is avertical section through a portion of the chair on the line 4 4- of Fig. 1. Fig. 5 is a rear View of my improvements relating to the back of the chair, and Fig. 6 is a section therethrough on the line 6 6 of Fig. 5.

The side frames, A A, of the chair comprise the leg portions a and a supplemental or guide frame, a. The said supplemental frame may be either cast separately and then bolted to the leg-frames a or the leg-frames and the guide-frame may be cast in one piece. It is preferable to cast the leg-frames and guideframe in separate pieces and then bolt them together, as thereby accurate adjustment or leveling of the chair may be secured. The

lower ends of the guide-frame a are preferably connected bya brace, which may either be formed when casting the guide-frame or be (No model.)

subsequently bolted thereto. It will thus be seen that the leg-frames and guide-frame virtually constitute a single frame. The inner faces of the guide-frame a, as at a (E, are grooved or recessed, so as to receive and guide a slide frame, B, which is provided with guides or ribs b, as clearly shown in Figs. 3 and 4 of the drawings. The slide-frame constitutes the Vertically-adjustable portion of the chair, and mounted upon its upper end is the seat-frame B of the chair, said slide-frame and the seat-frame being preferably rigidly united together.

In order to adjust the seat-frame by means 6 5 of the slide-frame vertically, so as to secure the desired altitude of the patient who is to undergo an operation while seated in the chair, I employ a new elevating mechanism, invented by me, which consists of a cycloidal or irregular figure, O, the outer edge or periphery of which is preferably substantially an involute curve, and mount said plate or figure on an axis, 0, about which said figure may be turned, as will hereinafterbe fully eX- plained. The said irregular figure is preferably mounted so as to turn upon a shaft or spindle, a, passing through the upper end of the supplemental or guide frame a, before described. Said plate or figure O is fitted to 8c turn within the guide-frame and slide-frame of the chair, so as to be inclosed and avoid all danger of interference with outside objects.

Upon the outer periphery of said plate or figure O are in this instance gear-teeth c, 8 5 and on one side thereof, preferably, is a peripheral flange, 0 on the same curve as the teeth of the plate. This peripheral flange may, however, be on both sides of the gearteeth. The gear-teeth are for the purpose of 0 giving motion to the plate or irregular figure 0 upon its axis, while the flange c bears the weight of the chair-body and of the occupant, so as to take the strain off said teeth.

In suitable bearings in the upper end of the 5 slide-frame B is journaled a pinion-wheel, D, on one side of which, and mounted upon the ,same shaft, D, as said pinion D, is a plain friction roller or collar, d, which bears upon the flange c of the figure 0, above described. The teeth of the pinion D are in this instance of a reduced diameter relatively to the periphery of the roller cl, and the elevating or thrusting strain on the pinion is consequently avoided.

A suitable crank or handle or other driv-' ing connection is connected with the shaft D, to rotate it in its hearings in the slide-frame B. A ratchet-wheel, E, is mounted upon said shaft D, and its teeth are engaged by a pawl, e, pivoted to the slide-frame B, whereby back movement of said frame and the chair-body carried thereby is prevented until the pawl is disengaged, and consequently any elevation or upward movement imparted to said frame B is preserved and the adjustment maintained in a rigid manner. Any other suitable clut ching device may be substituted for the ratchet and pawl.

In the elevating operation the shaft D is turned by its crank or driving connection. The rotation of the driving-pinion D imparts motion to the plate or irregular figure 0 upon its axis, and as the distance from its axis to its periphery is gradually increased relatively to the sliding driving mechanismduring the turning movement of the figure it will be obvious that the slide-frame B will be moved upward in its guides and the chair-body and patient seated therein elevated by the elevatingaction of the curved flange c on the roller or collar d. This increase of distance from the axis of the figure to its flanged periphery while said figure is being turned on its axis is gradual, and causes the elevating action imparted to the frame B.

The organization is such that with but little force applied to the shaft of the driving-pinion the pinion can be rotated, and by the elevating action of the curved figure comparatively heavy objects can be elevated or lowered. The curved figure may be provided at its outer end with a'suitable stop or abutment to limit its movement about its axis between the slideframe B.

The side pieces of the slide-frame B are bolted tether at the rear by a suitable brace, b, and at the front by a suitable apron, b, which closes the front portion of said slideframe,and thereby prevents the clothing of the patient from becoming entangled with the elevating mechanism. Said apron also enables the chair to be nicely finished and adds to its attractiveness.

The front ends of the side pieces of the slideframe B are preferably extended or prolonged at the front of the chair so as to constitute a connection for the usual foot-board and footrest of the chair. The rear ends of the slideframe B are fitted with an axis-bolt, f, on which is pivoted the extreme lower ends of the back-frame F, with the capacity in said back-frame of being adjusted backward and forward relatively to the seat of the chair about said bolt as an axis.

in the desired position. The rear ends of these arms G G are pin-jointed or pivoted to the back-frame, while in the organization shown in Figs. 1 and 4 the front ends of said arms are longitudinally slotted, as at g.

A bolt, H, is passed through the seat-frame of the chair and through the slots of the arms G G, and carries at one end a suitable clampnut or handle, 9, whereby it will be obvious that the arms G G may be slid or adjusted backward and forward on said clamp-bolt H, and then be securely clamped in their adj usted position by tightening the handle or clampnut above described. It will thus be obvious that all that is necessary to adjust the back of the chair backward and forward relatively to the seat is to loosen the clamp which binds the arms to the seat, adjust said back, and then reelamp the arms.

In place of a stationary clampbolt with slotted arms connected with the back, it will be obvious that the arms may be pivoted upon a clamp-bolt fitted to move back and forthin gnideslots in the seat-frame, as shown in Fig. 6.

The backframe may carry either a st-ati onary or an adjustable back pad or rest, and said back-pad of said back-frame will also be provided with a suitable adjustable headrest of any approved construction.

In order to clamp the chair securely in its elevated position, as determined by adjusting the slide-frame in the guide-frame or stationary part of the chair, I mount the cycloidal or irregular figure 0 upon a clamp-spindle fitted at one end with a lever clamp-nut, 0'', whereby said lever may be turned or tightened upon said spindle, and-thereby pinch or clamp together the slideframe and guideframe and said slideframe upon the hub c of the figure 0, whereby no elevation or low ering of the chair can be effected until said clamplever is released.

In Figs. 5 and 6 I have shown the backframe F as continued from the sliding arms G G into a lateral bar or strip, I, which is provided with a curved slot, i. The tubular rod J constitutes part of the back-frame F, and is jointed at its lower end by a joint, j, so as to be capable of rocking laterally upon a vertically-rocking joint, K. Said tubular rod J is fitted to receive a tubular rod, L, which telescopes in said rod J, and is locked in the desired position by means of a set-screw, j. This telescoping rod L carries the back-pad M, which is hinged to said rod at its upper end, as shown at m, whereby the back-pad hangs loosely from its pivotal connection. Said back-pad obviously is adjusted vertically by sliding the rod L in and out of the tubular rod J. Said tubular rod L in turn is fitted to receive the vertically-adjustable head-rest rod N, which carries a suitable rocking clampjoint, 0, to receive the backward and forward adjustable head-rest bar P, carrying the headrest pad P.

It will be understood, of course, that my im- 'proved chair may be fitted with any suitable adjustable head-rest devices.

In order to enable the chair-back and pad carried thereby to be inclined backward and forward relatively to the chair-seat,there is a slotted connection between the arms of the chair and the chair-seat, as before described, and,in addition,the chair-back is hinged to the chair-seat by the jointed connection K, which permits the backward and forward rocking of the chair-back, as before described.

In order to enable the rod J to yield to accommodate this backward and forward adjustment of the chair-back, it is connected with the lateral strip or bar I by means of a rocking forked clamp, Q, the members of which are pivoted to said tubular rod J, as clearly shown in Fig. 6. The screw-threaded shank q of said forked clamp passes through the curved slot i in the bar I, and is fitted with aclamp-screw handle,R. By this forked clamp not only the free backward and forward rocking of the backframe and pad carried thereby is permitted, but the lateral adj ustment of said back-pad relatively to the chair-seat is also permitted, owing to the pivotal connection j at the lower end of the rod J and the movement of the shank of the clamp in the curved slot in the bar I.

To secure the lateral adjustment of the chairback, it is only necessary to loosen the clampscrew handle R and rock the pad to either side desired. By tightening the clamp-lever it will be obvious saidback-pad will be firmly locked in its adjusted position.

I do not claim herein, broadly, a pivoted back to be adjusted backward and forward relatively to the chair-seat, in connection with jointed slotted arms, as that is shown in Gerwigs patent of May 16, 1882; nor do I claim a head-rest pad mounted on a support adjustable backward and forward and laterally relatively to a chair-seat, as that is old, being shown in O. O. Whites patent of July 6,1875, No. 165,286.

Having thus fully described my improvements, what I claim herein as my invention is- 1. The combination, substantially as hereinbefore set forth, of the base of the chair, the cycloidal lifting figure mounted in said base, the slide-frame carrying the seat-frame of the chair and fitted to slide vertically in said base, the elevating-shaft mounted in said slide-frame geared with said lifting figure to raise and lower said slide-frame and the parts of the chair carried thereby, and the detent to retain said slide-frame in its adjusted position.

2. The combination of the base of the chair, the slide-frame mounted therein and fitted to slide up and down, the cycloidal figure controlling the sliding movements of said slide-frame and fitted between the side pieces or members of said frame, the elevating shaft and pinion, and an independent clamp-bolt to clamp or bind the members of said slide-frame upon said lifting figure, substantially as described.

3. The combination of the seat-frame of the chair, the chair-back and back-pad, the pivotal connection between said seat-frame and said back, whereby said back may be adjusted backward and forward and laterally relatively to the chair-seat, the sliding arms also connecting the said back with said seatframe, the clamp connection between said arms and said seat-frame, whereby the backward and forward adjustment of said back is effected, and the laterally-sliding clamp-connection between said sliding arms and said back, whereby the lateral adjustment of the back-pad is effected, substantially as described.

In testimony whereof I have hereunto subscribed my name this 5th day of November, A. D. 1883.

\VILLIAM E. BURK.

Witnesses:

T. A. Lone, ELI S. MUSTIN. 

